>On Thu, 17 Dec 1998, Dave Celsnak wrote:
>
>> Hello,
>> Does anyone have experience interfacing a PIC to a Multi Media Card
>from
>> SanDisk?
>>
>> I am very interested in using a 4meg Flash memory card from them.
>


        Which gets me thinking (always dangerous!)...  In my last post, I
commented on my plans to add a 128 Kbyte RAM chip to a product to hold
user data.  Now, the user would, of course, like to safeguard that data
by having SOME sort of removable storage.  Removable memory cards are
expensive (compared to a floppy disk), and may not be a whole lot easier
to interface to.
        There was some previous discussion on the list about interfacing a PIC
to a floppy drive.  At the time I thought that was stupid!  Who would
want to use a floppy to save the contents of 200 or so bytes of RAM in a
PIC.  Now, of course, with 128 Kbytes of external RAM, I DO see some
value in external storage, and the floppy is looking nice.  The disks are
incredibly cheap; the drives are incredibly cheap.  All we need is a
version of DOS on a PIC so you can dedicate a PIC to driving the floppy,
then talk to that PIC through its serial port.  Anyone done ANYTHING like
this?
        About 15 years ago I designed a 6800 based product where I needed
external storage.  The first units used good old audio tape.  I then
wrote code to talk with Commodore (as one of my students pronounced it:
Commode Door) disk drives.  Those were kinda neat since they had the
operating system built in.  You just had to figure out how to talk thru
their serial bus.  I did that and sold a ton (a small ton) of products
that are still using the Commodore drive.  Something like that with the
PIC would be pretty neat.
        It would be CHEAP code you could drop into a PIC to make it a serially
controlled disk drive controller chip that writes IBM format on 3.5 inch
disks.  Anyone written that?


Harold


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